Put new rear wheel bearings in the car today. Everything went pretty good. Bearings in and out etc.

Put it back together and then took it for a spin. "4x4!" Shows up on the dash. And the DSC light. Back in the shop it goes. Threw a datalog on it and neither rear speed sensor is showing speed when on the rack and moving.

We put the correct bearings in with the speed sensor side on the inside. For the speed sensor to read off of.

I ordered two new speed sensors for the rear of the car.

I checked codes. And the only visible ones are for the transfer case. Its pissed because it thinks the cars moving. But the speed sensor says it isn't.

How common is it for the speed sensor to die? I did some research and found it to be common. But just wanted to ask around.

What bearing went on? F.A.G.? If so, are you sure you know which side was the magnetic side? Seems kinda unlikely that both sensors stopped working. You can try spraying both ends with contact cleaner and making sure the mounting area on the knuckle is clean.

I did my wheel bearings a while back with F.A.G. bearings. It has black on one side and orange on the other. My understanding was the black was the magnetic side, so I pressed it in black side first with the red being on the side with the wheel

Additionally, the cruise control would not work and I was getting the yellow ABS, Brake and triangle with the arrow encircling it, and the ((ABS)) warning.

The car drove normally. I didn't notice any noise. I took it to Dinan, and after a relatively expensive diagnosis, they told me that I a left wheel bearing assembly was defective.

I first tried replacing the sensors, and cleaning out where the attach to the hub. It was a cheap and easy job--but it was not the problem.

So I ordered bearings from a site called partsgeek.com. They were about $90 per wheel, and new axle nuts (about $9). I also went to Harbor Freight Tools and purchased a bearing separator (about $20) and Front Wheel Bearing Adapter kit (about $100). And after a lot of trial and error (and maybe a little cussing), I replaced both bearings.

I got into the car, and took it for a test drive. Everything was great with the ride, but all of the same lights came on--and more. The word "Brake" turned red, and the Airbag light came on, and I had no speedometer.

I ended up purchasing a second set of bearings from BMW (about $140 each), and interestingly they looked identical to the Timkens I purchased previously. Turns out that the first set I purchased were boxed incorrectly (or??) because they did not have the magnetic sensors. I put in the BMW bearings, and drove the car--and everything is back to normal. All lights out, and speedo and cruise control work again.

So this is what my experience suggests.

1. If you get the three lights, you need to replace a rear wheel bearing.
2. If, in addition to the three lights, your speedo doesn't work--its your right rear wheel bearing that is bad.
3. If, in addition to the three lights, your cruise control doesn't work--is your left wheel bearing that is bad.
4. If, in addition to the three lights, you have no speedo, no cruise control and your Airbag lights come on, then both rear bearings need to be replaced.
5. Although special tools are needed to do this job, it is possible to do as a DIY. The special tools you will need cost $120, and are pretty readily available. It can be pretty physical, but it is not all that complicated.
6. Although replacing the sensors is easy, they are probably not the problem. And no, cleaning them out will not fix the problem.
7. The system will reset itself when it gets a consistent signal from both wheel sensors.

Can you confirm the bearings are bad with a test that does not involve replacing them?..

Did you test the new sensors to see if they are sending signal through the wiring?

Can the computer receive those signals through the wiring connections?

Sometimes its a physical issue, like a connection problem or corroded wiring...very simple...Does the wiring have continuity where it should and the right amount of resistance ?
Im afraid Im being a bit vague here, but I hate to see you rip the whole thing apart if its something else.
I have trouble believing that the bearings are bad...but you never know. Can these bearings be "demagnetized" by a security check scan by Homeland Security????

Can you confirm the bearings are bad with a test that does not involve replacing them?..

Not really, unless by using a meter or oscilloscope to test, but that requires a known good ABS sensor.

Quote:

Originally Posted by 07lilredwagon

Did you test the new sensors to see if they are sending signal through the wiring?

They are BRAND NEW BMW equipment sensors.

Quote:

Originally Posted by 07lilredwagon

Can the computer receive those signals through the wiring connections?

The Computer shows No sign of any sensors. Old or New. When data logging the speed remains at "too low"

Quote:

Originally Posted by 07lilredwagon

Sometimes its a physical issue, like a connection problem or corroded wiring...very simple...Does the wiring have continuity where it should and the right amount of resistance ?

Agreed, all connections are secure. No idea what the correct resistance should be. Information is NOT out there.

Quote:

Originally Posted by 07lilredwagon

Im afraid Im being a bit vague here, but I hate to see you rip the whole thing apart if its something else.
I have trouble believing that the bearings are bad...but you never know. Can these bearings be "demagnetized" by a security check scan by Homeland Security????

best of luck with it!

JP

WHO knows. lol

All I know is, the car went into the shop working fine, but with bad bearings. The wheels were about to fall off. NO JOKE.

Changed bearings, and now neither rear speed sensor works. Replaced both Speed Sensors. and NO change. Ive seen it talked about where bearings were just BAD. I have a set of OEM BMW, which are branded SKF, bearings sitting here, and replacements from the auto store to replace the ones we purchased. We Purchased TIMKEN, which were branded *** on the bearing. The replacements from the store are Beck/Arnley, and I havent gotten my eyes on them yet. So we will see.

Put new rear wheel bearings in the car today. Everything went pretty good. Bearings in and out etc.

Put it back together and then took it for a spin. "4x4!" Shows up on the dash. And the DSC light. Back in the shop it goes. Threw a datalog on it and neither rear speed sensor is showing speed when on the rack and moving.

We put the correct bearings in with the speed sensor side on the inside. For the speed sensor to read off of.

I ordered two new speed sensors for the rear of the car.

I checked codes. And the only visible ones are for the transfer case. Its pissed because it thinks the cars moving. But the speed sensor says it isn't.

How common is it for the speed sensor to die? I did some research and found it to be common. But just wanted to ask around.

Well, I just might the answer to it.
IF I'm correct you have put aftermarket bearings into your car... right !?
Your speed sensor actually measures the amount of balls in the housing, yes that is right. So.... if you have ans aftermarket bearing with a different design ( more or less balls ) the gap between sensor and the balls is different than your OE bearing, you will be SOL, and you will have to replace them both.
I have had that exact issue with my EVO X before ( I almost lost it too ).
Now pressing bearing in and out, removing all of the hardware as you did, gives me an indication that you know how to work on your car, by saying that you are mechanically inclined .... Therefore if you did NOT have the any warning lights coming before the fix up, and now you do.... it is a simple case beware of parts that are cheaper ( there is a reason )

Your brake fluid is fine right? Doubtful that is the problem, but when I removed my rear sub-frame, my brake fluid level was very low and I did get lights for DSC and 4x4...I think. I remember thinking I had to check my speed sensor cable, but it was just because of low fluid levels.